feat: global publish method

[CS-Birb]

🔗 Linked issue

resolves #29

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Provides means for the crossws adapters that support pub/sub (bun, node and uws) to publish to a topic without holding onto a Peer. This will help support messages being initiated from other server contexts - rather than just in response to a Peer.

Open to input on alternative approaches - I expect this might not be quite at the desired quality just yet.

Not clear how this proposed feature would best integrate into downstream packages like h3 or Nitro. Open to any discussion!

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[pi0]

Hi. thanks for PR. Please see #61 for alternative approach. (we can implicitly access server instance from one of the peers considering publish only makes sense with at least one client)